Workflow for animating object inside of object? (Organic shapes...)
Use an armature with two bones, one for the heart and one for the wrap. Make the heart bone the parent of the wrap bone. Now when you scale the heart bone, the wrap will also scale.



You don't need to use weight painting, a simple parent object to bone will work. Parent the heart to the heart bone and the wrap to the wrap bone.



Now animate the scale of the bones -



You could also use shapekeys to give more detail during the pulsing.

Example here